Motion Reliability Assessment Calculation Of A Type Of Ventilation Isolation Valve Transmission System

Ventilation isolation valves are mainly used in air conditioning and ventilation systems of nuclear power plants.They are required to ensure proper ventilation and cooling function when they are open,and compacting seal with a self-locking function to meet leakage requirements when closed,futher in the event of an accident,they can play an important role in automatic isolation function for the system.Accuracy of motion transmited by ventilation isolation valve transmission system is key to sealing and self-locking performance of the valve.The purpose of this study is to evaluate and improve motion reliability of a type of ventilation isolation valve's transmission system,then to determine its reasonable precision plan of machining,assembly and maintenance.A comprehensive reliability assessment calculation method is proposed in this paper considering original errors in process of machining and assembly and errors due to wear and tear of hinge pairs during working process.Apply this method to conduct calculation analysis of transmission system's motion reliability as well as its sensitivity,which have a great significance on improving its reliability.Firstly,motion reliability analysis was conducted considering original errors.This study analyzed its structure characteristics and force condition,then built a valve plate closing reliability and self-locking reliability calculation model based on stress-strength interference model,established ADAMS models of valve plate and transmission mechanism to conduct simulations for many times,and futher determined the distribution of allowable limit output error considering the valve's seal and self-locking function requirements.Programed ADAMS language automatic simulation program to simulate and obtain output results data corresponding to a large number of input parameter values,futher abtained output error's distributions of valve plates closing angles and self-locking angles based on MonteCarlo theory,calculated and got reliability results according to calculation model built formerly.Secondly,wear reliability analysis of the transmission system's hinge pairs was conducted.A hinge pair's wear reliability calculation model was built based on the stress-strength interference model.Then distributions of allowable amount of wear and distributions of actual allowable amount of wear in work were determined,then the wear reliability was calculated.In the calculation process,the amount of wear formula was deduced based on the improved Archard wear model,and the hinge force and angular velocity functions were derived by ADAMS dynamic simulation and precisely fitting method,what's more,this study took sizes of hinge shafts and holes as random variables,simulated and got the distribution of the wear valve based on MonteCarlo theory,it's more accurate and closer to actual work condition.Furthermore,added the calculated amount of wear to the original errors,then conducted motion reliability analysis considering both original errors and hinge pairs' wear.Valve plate closing reliability and self-locking reliability were calculated.Finally,sensitivity analysis of reliability was conducted considering the transmission system's important parameters based on response surface method.First chose experimental method to get experimental sample points and then fitted limit state function by Design-Expert software,and further obtained the reliability performance function,then sensitivity of reliability was calculated through solving its derivative information for each random variable.The results shows that the parameters for sensitivity of the valve plate closing reliability is higher than sensitivity of the self-locking reliability.During the design process,the variance of each parameter should be reduced,,the mean value should be controled according to the trend of the sensitivity within the tolerance level.In the later detection and maintenance process,the parameters with higher reliability sensitivity should be paid more attention to.Scientific and rational processing,assembly and maintenance recommendations were proposed according to the calculation results.In conclusion,a comprehensive motion reliability calculation assessment method for ventilation isolation valve's transmission system is proposed in this paper,which will provide technical support for enterprise.